1. Field of the Invention
The invention relates to a free wheel hub in a four wheel drive automobile, especially the wiring connecting a battery to an actuator and a sensor set in the free wheel hub mechanism.
2. Description of the Prior Art
A prior art free wheel hub system is equipped with a sensor which indicates the operating condition of the free wheel hub to the driver and an actuator, like an electric motor, which changes the four wheel driving condition to the two wheel driving condition, in the axle hub or vice versa.
The prior art shown in FIG. 7 shows a free wheel hub system equiped with a switch sensor 2 so as to indicate the operating condition of the free wheel hub to the driver. When the free wheel hub system changes to the four wheel driving condition, by the operation of a hub ring 5 rotating with a drive shaft 3 and an inner hub 4, a roller case 7 moves to the left side shown in the FIG. 7 with a roller 6, and contacts a movable part 2a of the switch sensor 2 fixed on the outer side of spindle 1, and further the roller 6 engages a clutch housing 8 and the inner hub 4. Thereby the switch sensor 2 is switched ON and the transmitting of the driving force from the drive shaft 3 to the wheel is indicated. An indicator (not shown in FIG. 7) mounted in a clashboard is connected to the switch sensor 2 through an electric cord 9 which is wired through a hole 1A formed in the spindle 1, or as shown in FIG. 8, along a groove 1B formed on the inner face of the spindle 1.
The above mentioned free wheel hub system has the drawback in that the spindle 1 must have a reduced load, because the forming of the hole 1A or the groove 1B reduces the load spindle 1 can carry. Therefore, the transferable torque load of such a free wheel hub system is limited. Further it is impossible to design the hole 1A or the groove 1B to be large, and therefore the diameter of the electric cord 9 is limited. Thus, cord 9 may break down during assembly or as a result of the vibrations received from the wheel.
Thus the free wheel hub system is not reliable. Further, the greatest care must be used in mounting the drive shaft 3 to the spindle 1 or cord 9 will be broken. This process takes much time.